1. Field of the Invention
The instant disclosure relates to a method and a circuit for detecting a transmission and multiplexing configuration control (TMCC) signal; in particular, to a method and a circuit for detecting a TMCC signal used in an Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) system
2. Description of Related Art
The orthogonal frequency division multiplexing (OFDM) technology is a multi-carrier modulation technology of which the working principle is to divide a limited bandwidth into several sub-channels and to transmit data simultaneously by a plurality of sub-carriers that are mutually overlapped. By different modulation mechanisms, each sub-carrier can carry different amounts of data. Thus, compared with the traditional frequency division multiplexing (FDM) technology, the OFDM technology has a higher frequency band utilization rate and can prevent the effects that result from multi-path interferences.
The OFDM technology has been widely used in the current broadcast systems, such as the Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) system. The ISDB-T system and the standard thereof was established by Japan, and has become widely used in the South Africa. According to the standard of the ISDB-T system, the frame is a basic unit to transmit signals, wherein each frame is composed of 204 symbols and each symbol has 13 segments.
In each broadcast system, the parameter information, such as the carrier modulation mode, the interlace mode and the code rate of the convolution code, is all described in the transmission signal. After receiving the signal, a receiving device needs to demodulate the signal to obtain the above parameter information. After that, the receiving device can execute the de-interlace process, the video signal decompressing and the Viterbi decoding. According to the standard of the ISDB-T system, the TMCC signal has been especially defined for recording the above parameter information related to the signal. In addition, one symbol can only transmit one bit of the TMCC signal. Thus, an improved method and a circuit for detecting a TMCC signal is needed so that the receiving device in the ISDB-T system can detect the TMCC signal more quickly.